In ordinary inspection of an aircraft, there are some operations for inspection specific structural elements. Until know, looking for cracks are currently performed by shear waves ultrasonic inspection (UT). For example, one technique consists of coupling an UT probe on the surface of a lug in such a way that a UT beam is tangent to the circumference of the lug's hole. The optimum distance to the cracks depends on the lug thickness, the side of the lug where the crack is initiated, the cracks size, the angle of the probe applied on the lug, the probes size and the number of rebounds to reach the crack.
This type of inspection additionally implies a theoretical calculation or modeling of the optimum parameters and practical checking. Also, the inspection of lugs is not a static inspection of one point of the lug, consisting of look for cracks around the lug. This non-static inspection consists of sliding the probe around the circumference of the lug's hole ensuring that distance from the probe to the “expected crack” is kept optimum, and ensuring that UT beam is tangent to the lug circumference.
Unfortunately, it is difficult to comply with the above requirements disclosed. Consequently, dedicated support tools are defined to ensure proper probe sliding on the particular lug configuration. Thus, each operator must manufacture or buy, store and monitor periodically the tools defined in the maintenance manuals in order to perform this type of inspection.
Therefore, there is a need for a particular tool which makes easier and simpler the inspection of lugs, solving the problems of the state of the art.